Isomer shifts of sp impurities in metallic hosts

Isomer shifts for¹¹⁹Sn and¹²¹Sb impurities in different metallic hosts are compared. In the frame of the Miedema and van der Woude model three contributions to the isomer shifts due to the charge transfer, electron density mismatch and volume adjustment are calculated.     

Mössbauer study of Carpathian ferromanganese nodules

Ferromanganese nodules from Flysh deposits of West Carpathian Mountains were studied by Mössbauer spectroscopy method. The presence of small-grain goethite and hematite was established and grain sizes roughly estimated.     

PAC study of compound formation in the In-Pt system

The perturbed angular correlation technique was applied to measure the quadrupole interaction parameters of¹¹¹Cd at the In sites in electroplated In/Pt bilayers successively annealed at elevated temperatures. The consecutive creation of different compounds was evidenced by means of their PAC signal. The In₇Pt₃ andIn₃Pt₂ compounds were identified by comparison of the observed quadrupole interaction parameters with those measured for In-Pt bulk samples with defined stoichiometry.     

Intermetallic compound formation at the In-Pd interface investigated with111In local probes

The TDPAC technique was applied to study the formation of In-Pd compounds in bilayer electrodeposited sample doped with the radioactive¹¹¹In. Subsequent isochronal annealings at increasing temperatures caused the Pd diffusion into the In layer reflected in the quadrupole interactionR(t) curves. The appearing new unique frequencies indicate the formation of ordered In₃Pd, In₃Pd₂ andInPd₂ phases in the sample. The identification of this In-Pd compounds was based on the PAC measurements for bulk In-Pd samples with defined stoichiometry.     

Oxidation of ZrAl and Zr3Al compounds studied by181Ta-PAC spectroscopy

Hyperfine Interactions - The perturbed angular correlation method was applied to follow the oxidation processes in ZrAl and Zr3Al intermetallic compounds. It was found that the limiting temperature...     

Electric quadrupole interaction at 111Cd and 119Sn in isostructural NiIn and CoSn compounds

The perturbed angular correlation technique and Mössbauer spectroscopy were applied to study the electric field gradient on ¹¹¹Cd and ¹¹⁹Sn probe atoms in isostructural NiIn and CoSn compounds. The ¹¹¹Cd PAC measurements performed in the temperature range 80--1100 K demonstrated the existence of two axially symmetric EFG's in each of the investigated compounds, related to the 2(d) and 1(a) probe sites in the B35 structure. A 1(a)-site preference for Cd probes in CoSn compound was observed. The temperature dependence of the quadrupole frequencies for ¹¹¹Cd in both compounds, interpreted in terms of the empirical model proposed by Christiansen et al.[1], follows a T^3/2 relation with different slope parameters for each of the observed frequencies. These results are combined with the data from the Mössbauer experiment. The ¹¹⁹Sn Mössbauer spectra taken at liquid nitrogen and at room temperatures showed two quadrupole split doublets with the intensity ratio 2:1 for CoSn and 8:1 for NiIn_0.99Sn_0.01sample, giving an evidence of 2(d)-site preference for tin atoms in NiIn. The EFG values measured on ¹¹⁹Sn are 2.5 to 4 times larger than those on ¹¹¹Cd nuclei, while the ratio of the respective Sternheimer antishielding factors is equal to 0.77. Within the limits of errors no differences were observed in the magnitude and temperature dependence of Debye--Waller factors for 2(d) and 1(a) ¹¹⁹Sn positions in CoSn and NiIn lattices.     

Molecular dynamics and local electronic states of Sn and Fe in metallocytochrome and metalloporphyrin

In Sn-porphyrin tin appears in the Sn⁴⁺ state while in Sn-cytochrome c Sn⁴⁺ and Sn²⁺ states are observed. In Fe-porphyrin iron exhibits temperature-dependent mixed Fe²⁺-Fe³⁺ valency. In Fe-cytochrome iron is in the Fe³⁺ state. The bounded diffusion is observed in Fe-porphyrins above 300 K. The temperature dependence of the metal mean square displacement in cytochrome c and in Sn-porphyrin shows a deviation from the Debye model, which may be explained either by a new vibrational degree of freedom occurring above 150 K or by anharmonicity of the usual vibrations.     

Mössbauer study of tourmalines

The samples of tourmalines from Lower Silesia (Poland), belonging to the schorl-dravite series were studied. The ratio of Fe³⁺/Fe²⁺ ion concentrations were determined. The numbers and intensities of the main electric quadrupole doublets were explained assuming the random distribution of Fe, Mg and Al ions in the triads of octahedra Y.     

Determination of volatile organic compounds in human breath for Helicobacter pylori detection by SPME-GC/MS

Helicobacter pylori living in the human stomach release volatile organic compounds (VOCs) that can be detected in expired air. The aim of the study was the application of breath analysis for bacteria detection. It was accomplished by determination of VOCs characteristic for patients with H. pylori and the analysis of gases released by bacteria in suspension. Solid-phase microextraction was applied as a selective technique for preconcentration and isolation of analytes. Gas chromatography coupled with mass spectrometry was used for the separation and identification of volatile analytes in breath samples and bacterial headspace. For data calculation and processing, discriminant and factor analyses were used. Endogenous substances such as isobutane, 2-butanone and ethyl acetate were detected in the breath of persons with H. pylori in the stomach and in the gaseous mixture released by the bacteria strain but they were not identified in the breath of healthy volunteers. The canonical analysis of discrimination functions showed a strong difference between the three examined groups. Knowledge of substances emitted by H. pylori with the application of an optimized breath analysis method might become a very useful tool for noninvasive detection of this bacterium.